This invention relates to a process and apparatus for separating crude benzol and naphthalene from washing oil, and more particularly, to regenerating washing oil which has been spent to recover naphthalene and/or benzol from coke oven gas wherein the washing oil is regenerated by using steam to strip it of its volatile constituents to thereby enable resolving the volatile constituents into a number of fractions.
The crude gas occurring in the process of coking of coal contains, in addition to other substances, naphthalene and various hydrocarbons, particularly benzol, toluene and xylene which are grouped under the general designation of crude benzol. Naphthalene and crude benzol must be removed before the coke oven gas is put to further use. Naphthalene and crude benzol are removed usually by scrubbing the crude gas with washing oil which absorbs the naphthalene and crude benzol. It is known in the art to recover the naphthalene and crude benzol contained in the spent washing oil by distillation to thereby enable the reuse of the washing oil in the washing cycle. Distillation of the readily volatile components is effected with steam in order to avoid excessive oil temperatures and possible thermal damage to the oil during the distillation process.
The known processes for the regeneration of washing oil by means of steam usually yield two fractions, namely, the crude benzol, which contains all the hydrocarbons and other substances more volatile than naphthalene and naphthalene oil. The naphthalene oil is a mixture of naphthalene and washing oil with crude benzol fractions. Thus, on the one hand, there are considerable washing oil losses; while on the other hand, both fractions contain the required constituents, for example, benzol and naphthalene but in highly contaminated forms so that their sale value is reduced.